Touchless automatic car wash installations using spray arms which direct multiple streams of washing and rinsing fluids toward the surfaces of a stationary vehicle are popular due in large part to the fact that they generally make no hard physical contact with the vehicle and generally take up less space than traditional conveyor washers. Touchless systems commonly utilize one or more spray arms which are dependingly mounted from an overhead carriage which can be programmed for movement forward and backward longitudinally relative to a wash bay while the arm or combinations of arms can be programmed to move around the vehicle. An example of such system is fully disclosed in U.S. Pat. No. Re 40,463 assigned to Belanger, Inc. of Northville, Mich.
One of the features of the system described in the aforementioned patent is a breakaway joint which allows a spray arm or a lower portion thereof to be non-destructively angularly displaced out of its normal operating orientation. This is accomplished by a set of ball-detent joints operating about axes at 90° angles to one another. A spring-biased ball can be displaced out of a shallow socket and onto a flat raceway surface having a sharp corner with another flat raceway surface. Sensors are provided to produce a signal in the event either of the two joints breaks.
The joint just described must ordinarily be manually reset; i.e., the force of gravity working on the arm is not usually sufficient to compress the bias spring enough to allow the ball to go back around the sharp corner between the raceway surfaces.